The present exemplary embodiment relates to gas line piping systems and more particularly to an electrically insulated system which includes a dielectric fitting as part of the system. It finds particular application in conjunction with a dielectric fitting for a fuel conduit system so that the conduits are electrically insulated at a joint for preventing or retarding the flow of electricity over the dielectric fitting, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.
The connection between metal piping components such as pipes, conduits, unions or valves are prone to fluid or gas leaks due to the failure of a gasket or from corrosion caused by galvanic electric currents flowing across the connection. Further, corrosion is known to occur where the connection includes contact between two different types of metals while being exposed to an acidic solution. This combination effectively forms a battery which causes an electrical current to flow between the two metals such that molecules from one of the metals is deposited on the other, thereby resulting in galvanic electrolysis. To solve this problem, it is known in the art to use an electrically insulating member at the connection between the dissimilar metals to reduce or prevent electric current from flowing across the connection.
The 2011 edition of the National Fire Protection Association (NFPA) Code, Section 58, titled: Liquefied Petroleum Gas Code, requires a dielectric fitting at a building to electrically isolate the piping leading from a fuel tank from the piping in the building. Code section 6.9.3.16 states that underground metallic piping, tubing, or both that convey liquid petroleum (LP) gas from a gas storage container shall be provided with dielectric fittings at the building to electrically isolate it from the aboveground portion of the fixed piping system that enters a building. Such dielectric fittings are installed aboveground and outdoors. Compliance with this regulation is currently accomplished by installing a separate dielectric union at an inlet of a second stage regulator of a multi-stage regulator system. Notably, a multi-stage regulator system includes a first stage regulator to reduce gas pressure from a storage tank as it enters the gas lines and a second stage regulator to further decrease the pressure of the gas to a usable level for appliance demand. Second stage regulators are positioned by or in a building and work with the lower pressures delivered by first stage regulators to lower the pressure even more so that the LP gas will safely and adequately supply the demand of the appliances in the building or structure.
There are some types of dielectric fittings currently available. However, many of these fittings have insulation that is not optimally positioned between the metals due to the geometric orientation of the insulation. The insulation may be prone to shifting relative to the metal pipe joint, causing the pipes to contact each other thereby risking galvanic reaction. Further, the addition of a dielectric union to the second stage regulator in compliance with NFPA 58 adds cost to the overall system including the price for the additional materials as well as labor costs for installation. These additional connection points or joints also increase the risk of leakage in the system.
Therefore, there remains a need for minimizing the cost of labor and materials while maintaining compliance with NFPA code and reducing the risk of leaks within a fluid piping system.